The objective of this K01 award is to provide intensive mentoring and research training to the minority principal investigator that will allow for an effective transition into an independent academic researcher. The candidate will receive scientific and career mentorship from well established, highly motivational sponsors and advisory committee members. In the past, the investigator has focused on hematopoietic development. The proposed research will redirect her research to acquisiton of new skills in the areas of cardiovascular development and hypoxic biology. The proposal is based on work from Dr. Simon's laboratory encompassing work in hematopoiesis and vasculogenesis. Mutations in various subunits of the Hypoxia Inducible Factor (HIF) family, an important hypoxic transcriptional mediator, have contributed to the understanding the role 02 tension plays during early embryonic development. Abrogation of the Arnt subunit of the HIF heterodimer resulted in embryonic lethality by 10.5 days postcoitum (dpc) with yolk sac, placental, cardiac, and vascular defects. The goal of this proposal is to characterize the role of 02 in cardiovascular development, particularly on endothelial cells. The specific aims are to 1) determine how hypoxia influences endothelial behavior, 2) examine the hematopoietic and angiogenic potential of intraembryonic tissues of Amt -/- mice, and 3) determine the effect of hypoxia in heart development. Accomplishing these specific aims will provide an understanding of hypoxic signals in mediating biological responses required for the growth and differentiation of the cardiovascular system. Furthermore, the examination of the cellular and molecular responses to hypoxia will provide important insights into various disease states, including tumor growth, diabetic retinopathy, preeclampsia, wound healing, and ischemia. Additionally, the detailed studies of this proposal and the senior guidance of the faculty committee will assist in commanding the investigator into a leader in the field of cardiovascular biology.